OpenAI cuts GPT-5.6 Luna price 80% via self-optimization

OpenAI cut GPT-5.6 Luna's price 80% to 20 cents per million input tokens and $1.20 per million output tokens, undercutting most open-source Chinese frontier models. GPT-5.6 Soul, running inside Codex, rewrote GPU kernels and improved speculative decoding, cutting serving costs 20% and boosting token efficiency 15%.